Public screening is conducted at critical transportation and entry points. Most screening is conducted at airports, seaports, border crossings, high value civil infrastructure installations, and military bases. Currently employed methods to screen people against terrorist acts include physical searches, physical samples, and portal detection techniques to detect targets such as illegal drugs, explosives, and weapons.
In an example of present detection techniques in the laboratory, substance detection targets are identified by directing single-wavelength laser beams toward persons or specific areas. The presence of a target substance on the person or in the specific area is measured using spectroscopy methods.
Current detection devices employ various spectroscopy methods for detecting such target substances. Most present methods employ single-wavelength lasers to detect targets. The use of single-wavelength lasers exhibits shortcomings such as the occurrence of false positives and a failure to detect target substances due to an inherent reliance on a few data points from which to determine the existence of target substances. Accordingly, there is a need to provide an improved method of detecting target substances.